From: Tejun Heo <tj@kernel.org>
To: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Vivek Goyal <vgoyal@redhat.com>,
Andrew Morton <akpm@linux-foundation.org>,
avi@redhat.com, nate@cpanel.net, cl@linux-foundation.org,
oleg@redhat.com, axboe@kernel.dk, linux-kernel@vger.kernel.org
Subject: Re: [PATCHSET] block, mempool, percpu: implement percpu mempool and fix blkcg percpu alloc deadlock
Date: Wed, 4 Jan 2012 17:28:42 -0800 [thread overview]
Message-ID: <20120105012842.GQ31746@google.com> (raw)
In-Reply-To: <20111228004102.GK17712@google.com>
On Tue, Dec 27, 2011 at 04:41:02PM -0800, Tejun Heo wrote:
> Hello,
>
> On Wed, Dec 28, 2011 at 09:14:02AM +0900, KAMEZAWA Hiroyuki wrote:
> > > This is essentially more specialized form of the mempool approach. It
> > > doesn't seem any simpler to me while being less generic. I don't see
> > > what the upside would be.
> >
> > Hm, but this never causes -ENOMEM error, at all.
>
> Ooh, I missed the part it falls back to the global counter if percpu
> counters aren't allocated yet. Yeah, this is an interesting approach.
> I'll think more about it.
I've been staring at the blkcg stats code and commit logs and am
wondering whether we can just scrap percpu counters there. It seems
the reason why it was introduced in the first place is to avoid
stats->lock, which BTW is extremely heavy handed for gathering stats,
overhead in fast paths and I think there can be easier ways to avoid
stats->lock.
Thanks.
--
tejun
next prev parent reply other threads:[~2012-01-05 1:28 UTC|newest]
Thread overview: 51+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-12-22 21:45 [PATCHSET] block, mempool, percpu: implement percpu mempool and fix blkcg percpu alloc deadlock Tejun Heo
2011-12-22 21:45 ` [PATCH 1/7] mempool: fix and document synchronization and memory barrier usage Tejun Heo
2011-12-22 21:45 ` [PATCH 2/7] mempool: drop unnecessary and incorrect BUG_ON() from mempool_destroy() Tejun Heo
2011-12-22 21:45 ` [PATCH 3/7] mempool: fix first round failure behavior Tejun Heo
2011-12-22 21:45 ` [PATCH 4/7] mempool: factor out mempool_fill() Tejun Heo
2011-12-22 21:45 ` [PATCH 5/7] mempool: separate out __mempool_create() Tejun Heo
2011-12-22 21:45 ` [PATCH 6/7] mempool, percpu: implement percpu mempool Tejun Heo
2011-12-22 21:45 ` [PATCH 7/7] block: fix deadlock through percpu allocation in blk-cgroup Tejun Heo
2011-12-23 1:00 ` Vivek Goyal
2011-12-23 22:54 ` Tejun Heo
2011-12-22 21:59 ` [PATCHSET] block, mempool, percpu: implement percpu mempool and fix blkcg percpu alloc deadlock Andrew Morton
2011-12-22 22:09 ` Tejun Heo
2011-12-22 22:20 ` Andrew Morton
2011-12-22 22:41 ` Tejun Heo
2011-12-22 22:54 ` Andrew Morton
2011-12-22 23:00 ` Tejun Heo
2011-12-22 23:16 ` Andrew Morton
2011-12-22 23:24 ` Tejun Heo
2011-12-22 23:41 ` Andrew Morton
2011-12-22 23:54 ` Tejun Heo
2011-12-23 1:14 ` Andrew Morton
2011-12-23 15:17 ` Vivek Goyal
2011-12-27 18:34 ` Tejun Heo
2011-12-27 21:20 ` Andrew Morton
2011-12-27 21:44 ` Tejun Heo
2011-12-27 21:58 ` Andrew Morton
2011-12-27 22:22 ` Tejun Heo
2011-12-23 1:21 ` Vivek Goyal
2011-12-23 1:38 ` Andrew Morton
2011-12-23 2:54 ` Vivek Goyal
2011-12-23 3:11 ` Andrew Morton
2011-12-23 14:58 ` Vivek Goyal
2011-12-27 21:25 ` Andrew Morton
2011-12-27 22:07 ` Tejun Heo
2011-12-27 22:21 ` Andrew Morton
2011-12-27 22:30 ` Tejun Heo
2012-01-16 15:26 ` Vivek Goyal
2011-12-23 1:40 ` Vivek Goyal
2011-12-23 1:58 ` Andrew Morton
2011-12-23 2:56 ` Vivek Goyal
2011-12-26 6:05 ` KAMEZAWA Hiroyuki
2011-12-27 17:52 ` Tejun Heo
2011-12-28 0:14 ` KAMEZAWA Hiroyuki
2011-12-28 0:41 ` Tejun Heo
2012-01-05 1:28 ` Tejun Heo [this message]
2012-01-16 15:28 ` Vivek Goyal
2012-02-09 23:58 ` Tejun Heo
2012-02-10 16:26 ` Vivek Goyal
2012-02-13 22:31 ` Tejun Heo
2012-02-15 15:43 ` Vivek Goyal
2011-12-23 14:46 ` Vivek Goyal
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